1. Field of the Invention
The present invention relates to a method and apparatus for sorting objects in a production line for a sweet stuff, a foodstuff, or the like and, more particularly, to a sorting method for sorting, in the stage of packaging in the production line, objects such as, for example, pieces of biscuit, into groups of a predetermined number of pieces each, as they are continuously transported at predetermined intervals.
2. Description of the Prior Art
Hitherto, there have been known sorting apparatus of the type which sorts pieces of biscuit into groups of a specified number of pieces each as they are continuously supplied on a transport mechanism, such as a belt conveyor. A typical arrangement of such apparatus is illustrated, by way of example, in FIGS. 10 and 11.
The sorting apparatus shown has, at the downstream end of an upstream transport path 1, a sorting section provided in continuation therefrom and having a transport plane 20, the sorting section being upwardly inclined toward its downstream end (righthand side in FIG. 10). Below the transport plane 20 there are disposed a pair of chains C, C in parallel relation to each other for movement in parallel with the transport plane 20. On each of the chains C, C there are mounted brackets 39, . . . at given intervals, with fixed pins 41 individually mounted to the brackets. Each two corresponding fixed pins of those on the pair of chains C, C, right and left, make a pair and they extend upward from the transport plane 20.
On each of the chains C, C and between each two adjacent fixed pins 41, 41 there are disposed a plurality of up and down movable pins 40, . . . in the direction of transport. Similarly to the fixed pins 41, . . . , the up and down movable pins 40, . . . are arranged in pairs, each pair consisting of two corresponding ones of those disposed on the right and left chains C, C. The up and down movable pins 40 are up and down movably disposed on brackets 39 mounted to the chains C, C and are biased downward by springs 43. The mounting position for each up and down movable pin 40 is set so that the upper end of the pin 40, at its lowered position, is positioned lower than the transport plane 20.
The chains C, C are of such arrangement that they travel along a loop path running between the upstream and downstream ends of the transport plane 20 and that the upper portion of the path of run of the chains C, C is parallel to the transport plane 20.
As FIG. 11 shows, there is provided a guide plate K between the pair of chains C, C. This guide plate K is parallel to the chains C, C over a predetermined distance from a location adjacent the starting point of the upper portion of the path of run of the chains, while on the downstream side thereof the guide plate K is gradually bent or inclined so that it gradually runs away from the upper portion of the path of run of the chains C, C. The lower ends of the up and down movable pins 40, . . . are in slide contact with the upper surface of the guide plate K.
In that region of the sorting section in which the guide plate K is positioned adjacent the upper portion of the path of run of the chains C, C, the lower ends of the up and down movable pins 40, 40, . . . which run in conjunction with the chains C, C are pushed up by the guide plate K so that the upper ends of the pins 40, 40 . . . project upward from the transport plane 20.
As can be seen from FIG. 10, the starting point of the upper portion of the path of run of the chains C, C is positioned at a lower level than and ahead (at righthand side) of the downstream end of the upstream transport path 1.
By setting the speed of transport on the upstream transport path 1 and the run speed of the chains C, C to given timing, therefore, individual pieces P.sub.1 . . . which are continuously transported on the upstream transport path at given intervals are each caused to drop into the space between an adjacent pair of fixed pins 41, 41 and an adjacent pair of up and down movable pins 40, 40 or into the space between adjacent pairs of up and down movable pins 40, 40 and 40, 40 as they are transferred onto the transport plane 20. Thus, individual pieces P.sub.1 are accommodated, one by one, between individual adjacent pairs of pins 40 and 41.
As the chains C, C move downstream, individual pairs of up and down movable pins 40, 40 are sequentially guided at their lower ends by the guide plate K under the biasing force of the springs 43 so that the upper ends of the pins 40, 40 are caused to sink to a level below the transport plane 20. Thereupon, individual pieces P.sub.1 which have been supported between pairs of up and down movable pins 40, 40 are each relieved of the support and accordingly they are sequentially allowed to slide by gravity on the transport plane 20 from the downstream side or higher level side toward the upstream side or lower level side fixed pins 41.
Thus, all the pieces P.sub.1 . . . between adjacent pairs of fixed pins 41, 41 are stacked one over another in the direction of transport by being supported by the upstream side pair of fixed pins 41, 41 whereby they are assembled into one group of pieces P. A given space is defined between the downstream-most (i.e., the rightmost) piece P.sub.1 of this group of pieces P and a fixed pin pair 41, 41 downstream of the group. In other words, pieces P.sub.1 successively supplied are sequentially sorted into groups of pieces P so that groups of pieces P are successively formed at given intervals on the transport plane 20.
However, sorting apparatuses using such sorting method involve dimensional difficulties as mentioned below, which naturally requires the apparatus to be large in size.
(1) The sorting section for sorting pieces P.sub.1 supplied is required to be dimensionally long, which means that the apparatus is of a horizontally long construction.
As can be clearly seen from FIG. 10, the interval between adjacent groups of pieces P, P is greater than the sum of diameters of the up and down movable pins 40 . . . interposed between two adjacent fixed pins 41, 41. Therefore, where the number of up and down movable pins 40 . . . between the pair of fixed pins 41, 41, or the number of pieces P.sub.1 which constitutes each group of pieces P, is larger, the interval between the adjacent groups of pieces P is necessarily larger, with the result that a larger sorting section is required.
(2) A sufficient height difference must be provided between the upstream transport path 1 on one hand and the sorting section and a downstream working section continued from the downstream end thereof on the other hand, which necessitates increased size of the apparatus in the heightwise direction thereof.
Since the process of sorting pieces P.sub.1 is carried out by moving the individual pieces P.sub.1 by gravity toward the upstream side fixed pin 41, the transport plane 20 must have a given degree of angular inclination if such movement is to be smoothly carried out. To this end, sufficient difference of elevation must be provided between the upstream side of the transport plane 20 and the downstream side thereof and also in relation to a transport path and working section continued from the downstream end of the transport plane 20.